The primary objective of this research proposal focuses upon specific organism-environment interactions which are associated with marked cardiovascular alterations and may play a participant role in the pathogenesis of cardiovascular disease. In order to delineate the nature and extent to which such environmental-behavioral factors contribute to the development and maintenance of enduring circulatory changes, laboratory primates (baboons) will be systematically exposed to operant conditioning procedures involving the reinforcement (e.g., food-reward, shock-avoidance) of acute and chronic alterations of the systemic circulation. Circulatory and related functions (e.g., cardiac output, baroreceptor sensitivity, plasma renin-angiotensin-aldosterone and catecholamine levels) will be monitored in the conscious animal over extended intervals (months to years) in order to analyze the physiological mechanisms which mediate behaviorally induced changes in vascular pressure, peripheral resistance, and heart rate. The role of neural and hormonal regulation of the cardiovascular system under such circumstances will be assessed by autonomic neural blockage studies, and biochemical assays.